The NDIS responded to a recent Freedom of Information (FoI) request providing an email sent to a reporter containing:

 The following table combines data in the email and data from  the NDIS website (m-mASD means 'mild to moderate autism') ...

data from https://www.righttoknow.org.au/request/13542/response/43873/attach/7/FOI%2025.26%200499%20Decision%20Documents.pdf and https://dataresearch.ndis.gov.au/media/4366/download

The per cent 'mild or moderate autism' numbers above are calculated from the data sources as follows ...

All ASD aged 0-8 years is 53K (from NDIS data published on their website). All DD is 82.7K (same source). Subtract the DD from the combined 120.4K (in the FoI) to get 37.8K m+mASD in the 0-8 yo age range. 37.8K is 71.2% of 53K (all ASD 0-8yo).

So, the NDIS's media section told a journalist that 71.2% of young autistic children in the NDIS have 'mild to moderate' ASD ... presumably this proportion of autistic participants will be ineligible for the NDIS in future; those children, as well as the autistic children who are already ineligible for the NDIS, will need to access Thriving Kids or Foundational Supports instead ... once those programs are underway.

It seems that the NDIS sees its internal 1-5 severity rating as 'mild' when applied to autism (this is consistent with FoI response 25/26-0132 that describes "Participants with Autism as primary disability and high level of function (1-5)") and 6-10 severity as 'moderate', while 11-15 severity (ASD is never 15) is 'severe and profound' in the view of the NDIS. It is not clear what severity descriptor they use for autistic kids who they deem ineligible for the NDIS (like they did for HWSN for 6 months). This ignores that autistic kids should be severe (or more) to get into the NDIS in the first place ... and comparing NDIS numbers to ABS SDAC data (that is consistent with other sources) suggests that there are many autistic kids who do not ask for NDIS supports. 

Note: the NDIS severity reporting for autistic NDIS participants is deeply dodgy. The method is secret and I am not aware that its validity has been test or reported. 

71.2% is a huge proportion of 0-8 yo autistic NDIS participants to consider 'mild or moderate' ... given that most kids with ASD Level 1 do not apply to the NDIS (unlike kids with DD). We know this because the NDIS Quarterly Reports show a very high proportion of autistic applicants are accepted even though eligibility appears to be tested when the primary diagnosis is ASD L1. 

And GDD isn't mentioned in all this.

Why are these two disability types singled out? What about kids with mild or moderate disability (1-5 NDIS severity or more) of another type?

And then there's the NDIS saying only 17.6% (100% minus 82.4%) of 9-14 yo autistic NDIS participants have severe or profound disability. This level of severe and profound autism is well below other estimates (e.g. https://www.abs.gov.au/articles/autism-australia-2022).